Motor control.



PATENTED JUNE 4, 1907.

H. B. EMERSON. MOTOR CONTROL.

APPLICATION FILED 00117, 1906.

2 SHEETSSHEET 1.

\nvzn bot Hem B Emerson. W

Afly.

PATENTED JUNE 4, 1907.

H. B. EMERSON.

MOTOR CONTROL.

APPLICATION FILED 00117, 1906.

2 SEEETSSHEET 2.

Wicnesses \nventor Henry BEmerson. M

Act'y.

, similar machinery,

my invention; Fig. 2 s

, connected to the UNITED STATES PATENT orrroa.

HENRY B. EMERSON, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

moron CONTROL.

Application filed October 17,1906. Serial No. 339,323.

Specification of Letters Patent.

Patented June 4, 1907.

To all whom it may concern.-

Be it known that I, HENRY B. EMERSON, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful iImprovements in Motor Control, of which the following is a specification.

My invention relates to the control of motor-driven devices, such as printing-presses, which must be operated at widely varying speeds.

It has been proposed heretofore to employ two motorsfor driving printing-presses and one motor being of small capacity connected to the load through lowspeed gearing, and the other a larger motor load through high-speed gearing, With such an arrangement it is ordinarily necessary to provide means for mechanically disconnecting the smaller motor from the load when the load is being driven by the larger motor.

My invention comprises a novel arrangement of themotors and gearing and of the motor-control, whereby both motors may be mechanically connected to the load at all times. To this end I provide a differential gear having two of its members connected to the two motors, respectively, and the thirdto the load; the gearing being so arranged as to give a load-speed of'zero when the small motor is operating at its maximum, .and the larger motor at its minimum, speed. Iprovide controlling means for bringing the motors up to their maximum and minimum speeds, respectively; then gradually slowing down. and stopping the small motor; and then gradually accelerating the larger motor. In this manner an even acceleration of the load from zero to maximum speed is obtained, without disconnecting either-,motor from the load.

My invention'will best be understood by reference to the accompanying drawings, in which Figure 1 shows a side elevation of two motors and gearing arran ed in accordance with ows an end elevation of the same; and Fig. 3 is a diagram of the circuit connections and control switches.

Referring first to Figs. 1 and 2, A represents a large motor, and B a small'motor. The armature of motor A carries fast on its shaft a pinion c, which forms one member of a differential gear. A wheel C sleeved on the shaft of motor A is provided with both external and internal gears, the internal gear teeth forming a second member of the differential gear. The motor B carries on its shaft a worm d engaging a worm-wheel I). This wor1nwheel is provided with a plurality of studs on which are mounted the pinions c, which mesh-both with pinion c and with the internal gear teeth on wheel C and form the third member of the differential gear. The external ear on wheel C meshes with'ithe gear E, which is connected to the load. The gearing is so proportioned that when motor A is o crating at its minimum speed, and motor at its maximum speed, the wheel C stands still so that the load-speed is zero. By (gradually slowing down the motor B, a

a ual acceleration is imparted to the wheel and when motor B is brought to rest the pinions c act simply as idlers to transmit power directly from the pinion c to the wheel C. Then by increasing the speed of motor A the speed of the load may be further increased. "In slowing down the motor B the load-torque tends to drive motor B as a generator to return power to the line, and if the pitch of the worm is such that torque can be transmitted in both directions, the motor B will actually return a certain amount of power in this manner. If the pitch of the worm is such that power cannot be returned from the gear I) to the motor B, the motor B will simply run idle, taking only suflicient power to rotate the worm and allow the worm-wheel to revolve.

A suitable arrangement of control-circuits is shown in Fig. 3. Inthis figure the armatures of the two motors are represented by A and B, respectively, and the fields by a and b. F and 1' represent electrically controlled brakes of any well-known type, which, when the ma net-coils are deenergized, are mechanica ly applied, and which are electrically released. G1 and G represent two magnetically actuated switches or contactors for closing the circuits of the motor armatures. H represents a relay, will appear I and. represent armature resistances, and J" and J field resistancesv K represents the controlling switch comprising stationary contacts it" to it, and movable contacts 1 .to 26. L and L represent the line-wires leading roo the purpose of which from the following description.

' and G do .not drop their contacts.

from the source of current, and M and M represent push-buttons, the first of which is normally closed, and the second of which is normally open.

' The operation of the switches shown in Fig. 3 is as follows: With the controlling switch K in its off-position, the field-circuits only of the motors are closed. The field-circuit of the larger motor may be traced as follows: line-wire L, field-winding a, contacts 7c, 7c, 22, 25, and k, to line-wire L. The field-winding a is thus connected directly across the line with no resistance in circuit,- in other words, this field is at maximum strength. The circuit of field-winding b may be traced as follows: line-wire L, winding 1), contact lc, resistance J, contacts k, 26, 25, and k, to line-wire L. Field-winding b consequently .has all of resistance J in series with it, and is consequently at its minimum strength. When switchK is moved into its first running position a circuit is closed as follows: line-wire L, push-button M, contactor G, contacts k, 20, 2], 1c, Jr, 22, 25, and k, to line-wire L. Contactor G consequently closes its contacts. A second circuit may be traced as follows: line-wire L, contactor G, contacts 70", 19, 21, k, k, 22, 25, and k, to line-wire L. Contactor G consequently closes its contacts. It will be noted thateach of these contactors, in closing its contacts, closes a maintaining circuit for itself. The maintaining circuit of the contactor G extends through its second armature and contacts k, 16, 17, and is, to line-wire L, while the maintaining circuit for contactor G extends through 1ts lower contact and contacts k", 16, 17, k, to linewire L. Thus, when contacts 19 and 20 leave contacts 7c and lc", the contactors G Another circuit, which is closed as soonas contactor G picks up its contacts, is as follows: linewire L, bottom contacts of contactor G, brake-coil f, relay-windin H, contacts In, 18, 21, k k, 22, 25, and lg, to line-wire L. Brake-coil f consequently releases motorarmature B and relay H picks up, closing a maintaining-circuit for itself and for shuntcoil F throu h contacts In, 16, 17, 7c", to linewire L. he armature-circuits are also closed'in the first runnmg position of switch K,-as follows: line-wire contacts is, 1, 2, 76, to resistance 1. After this resistance, the current ing through the armature passing through ivides, part go- A, brake-coil F,

and upper contacts oficontactor G, to linewire L; the other part going through armature B, upper contacts of contactor G and upper contacts of contactor G, to line-wire L. Brake-coil F consequently releases armature A, and the arfnatures of both motors are connected across the line-wires with all of resistance I in series. As the switch K is moved to its second, third, fourth, fifth and sixth positions, no changes are made except that resistance I is cut out of circuit stepbystep, so as to bring the motor armatures A and B up to speed. It will be remembered that armature A is operated in full field, and consequently at minimum speed, while armature B is operating in its weakest field, and consequently at maximum speed, so that both at starting and when resistance I is entirely cut out, the loaddriven by the two motors will be stationary, since t 1e gearing is so designed that with armature A at minimum speed and armature B at maximum speed, the load-speed is zero. After resistance I is entirely out out, contact 26, which is carried by the movable part of switch K, and which has been moving along stationary contact strip is, now begins to pass over stationary contacts" k, so as gradually to cut resistance J out of circuit. This gradually stren thens the field of motor armature B, and s ows the armature down, thereby startin the load, as has been already explained.

en contact 26 reaches the stationary contact-strip k, the motor-field b is at full strength. When this point is reached mov able contacts 12 and 13 engage contact-fin- 'gers 7c and k, thereby short-circuitin contactor G by connecting both terml nals of the contactor winding to each other. This contactor consequently drops its contacts, thereby disconnecting motor armature B from the source of current. -At the same time motor armature B is short-circuited through the resistance I, in order to brake this armature electrically. This braking circuit may be traced as follows: from the right-hand brush of armature B, through contacts 7c, 7, 8, k, resistance I, to left-hand armature brush. As the controlling switch K is moved into the following positions, the resistance I is gradually'cut out. en armature B hasthus been brought to rest, or nearly to rest, the circuit of the brake-coilf is opened by the engagement of contacts 14 and 15 by the contacts k and 7:. contacts is and 7c are connected to opposite terminals of the relay H, which is conseuently short-circuited and drops its contact.

he circuit of brake-coil f is conse uently opened and the brake is applied, t ereby holding armature B stationary. The load is now being driven by the larger motor A along, which is still operating at its minimum s cc llWhile the circuit changes described above have been taking place, contact 22 has left contact it, while contacts 23 and 24 have come into engagement with contacts k and 1:. This transfers the circuit from the right-hand terminal of field-winding a to contacts 7c, 24, 23, k, k", 26, 25, and ii, to linewire L. Contact 26 has been moving over contact while motor armature B has been braked, and upon a further movement of the These two cuts this resistance J into circuit with field-winding A, so as'to increase the speed of controlling switch K, begins to move over the motor armature A, and further to increase the load-speed.

- As has appeared from the above description, the purposeof the relay II is to break the circuit of field-coil f at the proper time.

The purpose of the push-button M, which is normally closed, is to stop the motors instantaneously at any point in their operation. If this push-button M is depressed, the circult of contactor G is broken, so that it,

drops its armatures, opening the circuits oi both motor armatures and both brake-coils. The load is thus brought immediately to rest.'

The purpose of the maintaining contacts on the contactors and of the contacts 1.8, 19, and 21- is to prevent the motors from again starting up until the switch K is brought back to its first running position.

The purpose of the push-button M is to impart slow momentary movement to the load vention, it will be understoodthat the 'at starting, if desired. By depressing this push-button when the controlling switch K is in its starting, position, a section 01" resistance J is out out, so that a certain speed is imparted to the load.

While I have illustrated and described a complete control system applicable to my inarticular arrangement of the several 'contro ling switches shown is in no. way essential to my construction and arrangement of parts here shown, but'aim in the appended claims to cover all modifications which are-within the so? of my invention.

\at I claim as new and desire to secure by Letters Patent of the United States, is,'

1. In combination with a load to be driven, two variable-speed electric motors, and a differential gear having two of its members connected to said motors respectively and its third member to the load and arranged to give a load-speed of zero when one motor is operating at its maximum and the other at its minimum speed.

2. In combination with a load to be driven, two variable-speed electric motors of difierent capacities, and a differential gear having twoof its members connected to the two motors respectively and its third member to the load and arran ed to give a load-speed of Zero when the sma ler motor is operating at its maximum and the larger motor at its mim-" mum speed. I 3. In combination with a load to be driven, two-variable-speed electric motors, a diflerential gear-having two of its members contwo variable-speed electric motors of diilerent capacities, a diilerential gear having two of its members connected to the two motors respectively and its third member to the load and arranged to give a load-speed of zero maximum and the larger motor at its minimum speed, and an electrically-controlled brake for the gear member connected to the smaller motor.

5. In combination with a load to be driven, two variable-speed electric motors of difl'erent capacities, a differential gear having two of its members connected to the two motors respectively'and its third member to the load and arranged to 'give a load-speed of zero when the smaller motor is operating at its maximum and the larger motor at its minimum speed, and controlling means for said motors arranged to bring said motors to their maximum and minimum speeds respectively, then gradually to reduce the speed of the smaller motor and then gradually to increase the speed of the larger motor.

6. In combination with a load to be driven, two variable-speed electric motors of different capacities, a dillerential gear having two of its members connected to the two motors respectively and its third member to the load, and speed-reducing gearing in the connection between the smaller motor and the differential gear. 7. In combination with a load to be driven, two variable-speed electric motors of diiler ent capacities, a differential gear having two of its members connected to the two motors respectively and its third member to the load, speed-reducing gearing in the connection between the smaller motor and the differential gear, and controlling means for saidmotors arranged to bring the smaller motor to its maximum and the larger motor'to its minimum speed, then gradually to reduce the speed of .the smaller motor, and then gradually to increase the speed of the larger motor. 8. In combination with a load to be driven,

resistances for varying the field-strengths of the'motors, a differential gear having two of its members connected to the two motors respectively and its third member to the load, and arranged to give a load-speed of zero when the smaller motor is operating with minimum and the larger motor with maximum fieldstrength and a controlling switch arranged to bring said motors up' to speed simultaneously with minimum and maximum field-strengths respectively, then gradwhen the smaller motor is operating at its -two electric motors of diilerent capacities,"

ually to increase the field-strength of the smaller motor, and then gradually to decrease the field-strength of the larger motor.

9. In combination with a load to be driven, two electric motors of different capacities, resistances for varying the fieldstrengths of the motors, a differential gear having two of its members connected to the two motors respectively and its third member to the load, and arranged to give a load-speed of zero when .the smaller motor is operating with minimum and the larger motor with maximum field-strength, an electrically-controlled brake for the smaller motor, and a controlling switch arranged to bring said motors up to speed simultaneously with minimum and maximum field-strengths respectively, then gradually to increase the field-strength of the smaller motor, then to apply said brake, and then gradually to decrease the field-strength of the larger motor. y

10. In combination with a load to be driven, two electric motors of different capacities, resistances for varying the fieldstrengths of the motors, a differential gear 2 having two of its members connected to the two motors respectively and its third membcr to the load, and arranged to give a loadspeed of zero when the smaller motor is operating with minimum and the larger motor 3 with maximum field-strength, and a controlling switch arranged to brin said motors up to speed simultaneously wit minimum and maximum field-strengths respectively, then gradually to increase the field-strength of the 3 smaller motor, then to short-circuit the armature of the smaller motor, and then gradually to reduce the field-strength of the larger motor.

In witness whereofl'I have hereunto set 4 my hand this 16th day of October, 1906.

HENRY B. EMERSON.

' Witnesses:

BENJAMIN B. HULL, HELEN @RFORD. 

